Gas masks have been crucial objects in the Island's history. Different masks have belonged to members of the DHARMA Initiative, the Kahana's science team, and the Others.

History of Usage

Before the Crash

In 1992, the Hostiles orchestrated the Purge against the DHARMA Initiative using fatally toxic gas, presumably from the Tempest. In order to protect themselves from the deadly effects of the gas, the Hostiles, including Ben Linus, a defector from DHARMA, wore the masks until the gas had cleared and the air was once again safe. ("The Man Behind the Curtain")

Desmond confronts Daniel while wearing a gas mask ("Because You Left")

Kelvin Inman, a surviving member of DHARMA, wore a HAZMAT suit with a gas mask whenever traveling outside of his designated station, the Swan, because he believed the Island possessed an outdoor pathogen. Inman was wearing a mask when he rescued a shipwrecked Desmond Hume. At some point, however, Inman discovered that the outdoor pathogen did not exist, and, though he continued wearing the mask and the suit as a façade to fool Desmond Hume into remaining inside the Swan, he would remove the mask soon after exiting the station. ("Live Together, Die Alone, Part 1")

Desmond also wore a mask and a suit when he confronted Daniel Faraday, a victim of time travel, who was attempting to get Desmond to save them. ("Because You Left")

After the Crash

In late 2004, in order to keep themselves safe from stun gasses, the Others donned gas masks before gassing Kate, Jack, and Sayid. Juliet was also given a gas mask to protect herself from the gasses, but she later disposed of it in order to maintain the ruse that her people had left her behind, in order to gain Kate's trust. ("Left Behind")

Soon after this event, Naomi Dorrit, a science team member from the Kahana, parachuted onto the island. When she was found by Desmond, Charlie, Hurley, and Jin, she was wearing a high altitude oxygen mask to protect her from the thinner oxygen levels above. Desmond removed the mast after rescuing Naomi, discovering to his dismay that she was not Penny as he had previously believed. ("Catch-22")

Jack holds up a gas mask he found. ("Confirmed Dead")

The rest of the science team soon followed after Naomi, landing on the Island. However, due to a storm experienced while over the Island, they were forced to jettison a supply box from their helicopter. While traveling with Daniel Faraday, Jack discovered the box, and upon searching through it, discovered a gas mask. When he questioned Daniel about the mask, Daniel nervously replied that he "wasn't in charge of packing." ("Confirmed Dead")

Daniel later procured the gas mask (as well as another). Several days later, Kate discovered one of them in Daniel's pack. Before she could ask about it, however, Charlotte knocked her out in order to keep her quiet. Daniel and Charlotte then donned HAZMAT suits, including the gas masks, and continued on to the Tempest, where they attempted to shut down the station. Juliet soon interfered, however, believing that they were attempting to release the gas instead of attempting to disable it. In a fight caused by this misunderstanding, both Daniel and Charlotte's masks were ripped off. ("The Other Woman")